The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In a typical internal combustion engine operated using fuel, the fuel in a fuel tank is evaporated and collected in a canister. Subsequently, when the engine reaches a certain condition during the operation thereof, the fuel evaporation gas collected in the canister is transmitted to a surge tank due to a difference in pressure between the fuel tank and an intake manifold, and is then purged.
However, in a GDI (Gasoline Direct Injection) engine equipped with a turbocharger, since the pressure in an intake manifold is very high under the condition of turbo boosting, fuel evaporation gas collected in a canister is not purged. Accordingly, in order to cope with fuel odors and evaporation gas regulations, a separate method is required for the turbo-GDI engine.
FIG. 1 is a diagram illustrating a conventional dual purge system for a vehicle. As illustrated in FIG. 1, the dual purge system additionally includes a purge line in which a solenoid valve 50 is provided on an air suction line at the rear end of an air cleaner 40, in addition to an intake manifold 20, so as to purge fuel evaporation gas.
FIG. 2 is a view illustrating a conventional solenoid valve 50. An armature 55 and an elastic member 54 are operated along with the operation of a solenoid 53 when an engine 10 is in a purge condition, and thus an outlet 52 is opened. Thereby, a fluid (fuel evaporation gas) introduced from a lower inlet 51 of a valve body 56 is discharged to an intake manifold 20 through the opened outlet 52.
However, in the above case, check valves 60a and 60b, i.e. two check valves 60a and 60b are applied to respective purge lines for preventing the fluid from flowing backward, and the fuel evaporation gas evaporated from a fuel tank 70 is purged. For this reason, the system has a complex structure, there is a possibility of backflow, odors are generated, and a purge may not be normally performed.